Technical A Little Electrical Mystery

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Technical A Little Electrical Mystery

foolgladly

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Jun 17, 2016
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Hey guys, I've been surfing these forums for the last month since I purchased my 77 Spider 124 convertible, and it seems like the perfect place to post my first question.

Yesterday, I was doing a little maintenance. I put a new battery in and replaced my fuel sending unit (I had the apparently common "bouncing" fuel gauge, read through a bunch of posts here and went for it). The sending unit completely solved my fuel gauge issue (even after a test drive over some bumpy roads with less than half a tank), and the new battery with higher CCA made for much smoother starting.

After the test drive and with everything working perfectly, I did some digging around in the service manual and decided to make some minor carburetor adjustments to help with a low idle. I removed the air cleaner and housing to get a better look at where the idle screw and idle mixture screw are on the carb. After identifying their location, I put the air cleaner housing, filter and lid back in place, fired up the car and went about adjusting.

Some time after a few minor screw turns while listening to the engine, I peeked back at the gauges to see where she was idling. At that point, I realized I'd lost my tach. Shortly after that, I realized I'd lost all of my dash gauges. Clearly, I brushed up against something in the process and either shorted something out, blowing a fuse or disconnecting something.

I realize this post is long, and I apologize, but here's what's what: My only electrical dealings were changing the battery (quick, simple, and everything worked after doing so), and disconnecting and reconnecting the two electrical leads to the fuel sending unit (again, ridiculously simple and everything worked after reconnection). After that, I only did what I described above.

After further checking, here's what doesn't work: All gauges, headlights, wipers, turn signals, radio. What does work: Taillights with switch in middle position, courtesy light, horn, and the car fires up perfectly and runs great.

I'm posting this in such detail in the hopes that one of you brilliant folk will be able to help me to an "Aha!" moment. Is there a master fuse or relay of some sort? Is there something in my air cleaner/carburetor adjustment process that would have put me real close to something that I could have easily knocked out of position without noticing?

I checked the master ground between the block and the frame, and it's clean and rock solid.

One last note: on the drivers side of the engine compartment above the wheel well there are a bunch of white plastic electrical connectors that have not been connected to anything since I bought the car. I assume they're for options that weren't chosen for this particular vehicle, but it also makes it hard to know if there's now an extra one that used to be connected to something.

If you've read this far, you're a saint. I googled around a bunch and also checked through the forum, but I haven't found anything that quite matches my situation. Any help would be greatly appreciated!

Thanks again,

Chris
 
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